Current collector for a stacked battery design

ABSTRACT

Energy storage devices, battery cells, and batteries of the present technology may include a first cell and a second cell disposed adjacent the first cell. The devices may include a stacked current collector coupled between the first cell and the second cell. The current collector may include a grid or matrix, and may include a combination of conductive and insulative materials.

CROSS REFERENCES TO RELATED APPLICATION

The present application is a division of U.S. patent application Ser.No. 16/273,625, filed Feb. 12, 2019, which is a continuation ofPCT/US2017/052413 filed Sep. 20, 2017, which claims the benefits of U.S.Provisional Patent Application Ser. No. 62/398,185, filed Sep. 22, 2016,and U.S. Provisional Patent Application Ser. No. 62/461,535, filed Feb.21, 2017, the entire disclosures of which are hereby incorporated byreference for all purposes.

TECHNICAL FIELD

The present technology relates to batteries and battery components. Morespecifically, the present technology relates to current collectordesigns.

BACKGROUND

In battery-powered devices, penetration of the battery housing andinterior cells may occur during abuse conditions. A test for this typeof device condition involves a nail penetration in which the nailpunctures interior components of the battery. Improved designs fortesting outcomes are needed.

SUMMARY

The present technology relates to energy storage devices, includingbattery cells and batteries, which may include lithium-ion batterieshaving a variety of shapes including stacked cells, which may be orinclude bipolar batteries or mono cell stacked batteries, for example.These devices may include current collectors configured based on az-direction transmission of current through the cell components, ascompared to in-plane electrical transmission across current collectors.The current collectors may include a host of features and materialconfigurations as will be described throughout the disclosure.

Energy storage devices, battery cells, and batteries of the presenttechnology may include a first cell and a second cell disposed adjacentthe first cell. The devices may include stacked batteries havingadjoining current collectors. The devices may include a stacked currentcollector coupled between the first cell and the second cell. Thecurrent collector may include a grid or matrix, and may include acombination of conductive and insulative materials. In embodiments thestacked current collector may include a conductive material disposedwithin the insulative material.

The stacked current collector may prevent or substantially preventin-plane current flow through the stacked current collector inembodiments, or may have increased resistivity in-plane. For example, anin-plane resistivity of the stacked current collector may be greaterthan or about 0.005 ohm-meters across a length of the stacked currentcollector. In embodiments, the stacked current collector may include afirst layer in contact with the first cell, and a second layer incontact with the second cell. Additionally, an interface between thefirst layer and the second layer may be fluid impermeable.

In some embodiments, the first layer and the second layer may eachinclude an insulative grid having a conductive material disposed withinthe insulative grid. The conductive material disposed within theinsulative grid of the first layer and the second layer may be a similarmaterial, and in embodiments, the conductive material may be or includestainless steel. In some embodiments the conductive material may includea conductive composite material. Additionally, the stacked currentcollector may further include a coupling material positioned about aperimeter of the insulative grid.

The present technology also encompasses single-cell and multi-cellbatteries. In embodiments, the multi-cell batteries may include a firstcell, and the first cell may have a first current collector, a firstanode, a first cathode, and/or a second current collector. Themulti-cell batteries may also include a second cell, and the second cellmay have a third current collector, a second anode, a second cathode,and/or a fourth current collector. In embodiments, the second currentcollector and the third current collector may be coupled with oneanother across a surface of each of the second current collector and thethird current collector. Additionally, each current collector mayinclude a conductive grid. In embodiments at least one current collectormay also include a current interrupt component.

The conductive grid of each current collector of the multi-cell batterymay be disposed in an insulative material. In some embodiments thecurrent interrupt component may be or include a positive temperaturecoefficient (“PTC”) material disposed with the insulative material. ThePTC material may be configured to expand at a predetermined temperatureand separate the current collector from an adjacent component layer. Insome embodiments, the first current collector and the third currentcollector may include a first material in the conductive grid.Additionally, the second current collector and the fourth currentcollector may include in the conductive grid a second material differentfrom the first. For example, the first material may be or includealuminum and the second material may be or include stainless steel. Insome embodiments the conductive grid of each current collector may bethe same or a similar material.

The current interrupt component of the multi-cell batteries may includea plurality of regions of the at least one conductive grid. Inembodiments, the plurality of regions may be characterized by reduceddimensions in comparison to other regions of the conductive grid orother components. The grid may include a plurality of crossed gridmembers. In some embodiments the plurality of regions may includeparallel grid members characterized by a grid member thickness less thana grid member thickness of parallel crossing grid members. Additionally,the grid may include a plurality of crossed grid members, and theplurality of regions may include portions of the grid members locatedbetween grid nodes. The current interrupt component may also be orinclude a non-resettable positive temperature coefficient (“PTC”)material disposed between the second current collector and the thirdcurrent collector. In embodiments the PTC material may be configured toexpand at a predetermined temperature to electrically decouple the firstcell and the second cell.

Embodiments of the present technology may also encompass batteries.Exemplary batteries may include a first cell that may include a firstcurrent collector coupled with a first cathode material. The first cellmay also include a second current collector coupled with a first anodematerial. Exemplary batteries may also include a second cell that mayinclude a third current collector coupled with a second cathodematerial. The second cell may also include a fourth current collectorcoupled with a second anode material. In some embodiments the secondcurrent collector and the third current collector may be coupled withone another. Additionally, each current collector of the first cell andthe second cell may be or include an insulative matrix containing aconductive material within interstices of the insulative matrix.

The insulative matrix in exemplary batteries may include a polymermatrix. In some embodiments, the conductive material may include atleast one material selected from the group consisting of silver,aluminum, copper, stainless steel, and a carbon-containing material. Theconductive material may include alternative conductive materials aswell. In embodiments the resistivity of each current collector may begreater than or about 0.001 ohm-meters. In some exemplary batteries eachof the current collectors may further include a coupling materialpositioned about a perimeter of the current collector. The couplingmaterial may include a polymeric compound, and in embodiments thepolymeric compound may be or include a polyolefin.

Such technology may provide numerous benefits over conventionaltechnology. For example, the present devices may aid in failure eventsin which the integrity of the device is breached. Additionally, thedesigns may allow extended scaling of batteries for use in largerdevices and systems. These and other embodiments, along with many oftheir advantages and features, are described in more detail inconjunction with the below description and attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedembodiments may be realized by reference to the remaining portions ofthe specification and the drawings.

FIG. 1 shows a schematic cross-sectional view of an energy storagedevice according to embodiments of the present technology.

FIG. 2 shows a schematic cross-sectional view of a current collectoraccording to embodiments of the present technology.

FIG. 3 shows a top plan view of a portion of a current collectoraccording to embodiments of the present technology.

FIG. 4A shows a schematic cross-sectional view of a battery during afault event according to embodiments of the present technology.

FIG. 4B illustrates a temperature profile of a top plan view of abattery during a failure event from nail penetration according toembodiments of the present technology.

FIG. 5A shows a schematic cross-sectional view of a portion of a stackedbattery during a fault event according to embodiments of the presenttechnology

FIG. 5B illustrates a temperature profile of a top plan view of aportion of a current collector during a fault event according toembodiments of the present technology.

FIG. 6 shows an exemplary cross-sectional view along line A-A from FIG.3 of a current collector according to embodiments of the presenttechnology.

FIG. 7A shows an exemplary cross-sectional view of a current collectoraccording to embodiments of the present technology.

FIG. 7B shows an exemplary cross-sectional view of a current collectoraccording to embodiments of the present technology.

FIG. 8 shows an exemplary cross-sectional view of a battery cellaccording to embodiments of the present technology.

FIG. 9 shows a top plan view of a portion of a current collectoraccording to embodiments of the present technology.

FIG. 10A shows an exemplary schematic detailed view of region B fromFIG. 7 of a current collector according to embodiments of the presenttechnology.

FIG. 10B shows an exemplary schematic detailed view of region B fromFIG. 7 of a current collector according to embodiments of the presenttechnology.

FIG. 11 shows a cross-sectional view of an exemplary battery accordingto embodiments of the present technology.

FIG. 12 shows an exemplary schematic detailed view of region C from FIG.11 of a current collector according to embodiments of the presenttechnology.

Several of the figures are included as schematics. It is to beunderstood that the figures are for illustrative purposes, and are notto be considered of scale unless specifically stated to be of scale.Additionally, as schematics, the figures are provided to aidcomprehension and may not include all aspects or information compared torealistic representations, and may include additional or exaggeratedmaterial for illustrative purposes.

In the figures, similar components and/or features may have the samenumerical reference label. Further, various components of the same typemay be distinguished by following the reference label by a letter thatdistinguishes among the similar components and/or features. If only thefirst numerical reference label is used in the specification, thedescription is applicable to any one of the similar components and/orfeatures having the same first numerical reference label irrespective ofthe letter suffix.

DETAILED DESCRIPTION

Batteries, battery cells, and more generally energy storage devices, maybe made from a host of materials. In some conventional battery designs,such as in some lithium-ion batteries, the current of each cell isconducted across current collectors and through tabs at their exterior.During a discharging operation, current entering the device at the anodetypically enters through tabs on anode current collectors, and currentleaving the device at the cathode typically leaves through tabs oncathode current collectors. At the anode, for example, the current mustenter at the tab of what may be a copper current collector and thendistribute across the entire current collector. Put another way, thecurrent must distribute in-plane or along the XY-axes of the currentcollector, which is often in dimensions of the millimeter range or more.Because of this relatively large distance and area distribution on eachcurrent collector, the current collectors are often sought to be asconductive as possible, because as resistivity increases performance maydecrease, and additional heat may be generated in the device. This isoften why highly conductive materials, such as aluminum and copper, areused in many conventional current collector designs.

In stacked batteries, cells are stacked in series, but electrons flowthrough plane with respect to the current collector and cells, or alonga normal or Z-axis from the current collector. Stacked batteries ofteninclude at least one current collector that operates both as the anodeof one cell and the cathode of a paired cell. Another design called amono cell stack, or MCS, may have similar operational characteristics ofa stacked battery, but each cathode and anode have separate currentcollectors.

In terms of distance for stacked batteries, the electrons and currenttraverse a distance that is orthogonal to the individual layers.Accordingly, with the current collector, the electronic flow occursacross the thickness of the current collector, which may be on the orderof several microns or less, as opposed to across the length/width of thecurrent collector, which may be on the order of millimeters or more. Inthis way, conductivity of the current collector materials can be less ofan issue in terms of battery performance due to the small distancestraveled, and associated resistances, to pass electrons and currentthrough the device. Indeed, in some cases the entire thickness of thestacked cells of the battery through which current flows may be lessthan the distance across a single current collector in conventionaldesigns.

As devices increase in size, or power requirements increase, batteriesmay be scaled to provide adequate power. Battery testing may involve oneor more tests that breach the integrity of the cell, such as by nailpenetration, which may cause device failure as well as short circuiting.When conventional batteries are breached in such a way, the shortcircuit may breach any number of cells, and being coupled in seriesregardless of the extent of breach, the current from the entire devicemay travel to the short. Current flow generates heat both in operationand in short circuiting, although this heat generation may be muchgreater during a short-circuit event based on the degree oftransmission. This generation may be greater still for larger batteriesholding more charge, which can dissipate at a high rate acrosscomponents. Such a short may generate enough heat to risk integrity ofthe system.

Conventional battery designs have struggled with controlling heatgeneration from these and other possible failure events while attemptingto scale batteries to larger sizes, which can increase the extent ofheat generation from fault events. The present technology may overcomethese conventional issues with current collector designs that provideisolation or control of failure events. By isolating a breach, orcontrolling the extent or rate of electronic flow to a breach, thepresent technology may reduce heat generation during device failureconditions.

Although the remaining portions of the description will routinelyreference lithium-ion batteries, it will be readily understood by theskilled artisan that the technology is not so limited. The presentdesigns may be employed with any number of battery or energy storagedevices, including other rechargeable battery types as well asnon-rechargeable designs. Moreover, the present technology may beapplicable to batteries and energy storage devices used in any number oftechnologies that may include, without limitation, phones and mobiledevices, handheld electronic devices, laptops and other computers,appliances, heavy machinery, transportation equipment includingautomobiles, water-faring vessels, air travel equipment, and spacetravel equipment, as well as any other device that may use batteries orbenefit from the discussed designs. Accordingly, the disclosure andclaims are not to be considered limited to any particular examplediscussed, but can broadly be utilized with any number of devices thatmay exhibit some or all of the electrical or chemical characteristics ofthe discussed examples.

FIG. 1 depicts a schematic cross-sectional view of an energy storagedevice according to embodiments of the present technology. The energystorage devices may include a single current collector or coupledcurrent collectors. Additionally, the described devices may similarlyoperate by electronic flow through the structure in a Z-directionthrough individual cells as opposed to via tabbed current collectors asdescribed above for conventional batteries.

As illustrated, the stacked battery 100 may include a stack ofelectrochemical cells C1, C2, C3, and C4 between end plates 102 and 104.End plates 102 and 104 may be metal current collector plates, which canserve both electrical and mechanical functions. In some embodiments, endplates 102 and 104 can be support plates that form part of an externalhousing of the stacked battery. End plates 102 and 104 may also providemechanical support within a housing of the stacked battery. Some or allof the support plates may be electrically conductive, and there may be aterminal within the support plate that is electrically connected to theend plate. In embodiments an additional plate similar to end plates 102and 104 may be disposed within the stack of cells, such as between twocells. This configuration including an additional plate may providestructural rigidity, and the additional plate may also preformelectronic functions similar to end plates 102, 104. End plates 102 and104 may act as positive and negative terminals of the battery. The cellsmay pass current in the Z-direction through individual cells to the endplates, which may transfer current in any direction across the plate andfrom the battery.

The stack of electrochemical cells may include any number ofelectrochemical cells depending on the selected voltage for the stackedbattery 100, along with the individual voltage of each individualelectrochemical cell. The cell stack may be arranged with as many or asfew electrochemical cells in series as desired, as well as withintervening plates for support and current transfer. The cells C may bepositioned adjacent, e.g. abutting, one another in some configurations.Each electrochemical cell C may include a cathode 110 and an anode 120,where the cathode 110 and anode 120 may be separated by separator 130between the cathode and anode. Between the anode 120 of cell C1 and thecathode of adjacent cell C2 may be a stacked current collector 150. Thestacked current collector 150 may form part of C1 and C2. On one side,stacked current collector 150 may be connected to the seal 140 of C1 andconnected on an opposing side to the seal 140 of C2.

In some embodiments, as shown in FIG. 1 , stacked current collector 150may include a first metal layer 152 and a second metal layer 154. Asshown in the figure, in some embodiments the first metal layer 152 andsecond metal layer 154 can be different materials. In some embodiments,the first metal layer 152 may be a material selected based on thepotential of the anode 120, such as copper or any other suitable metal.The second metal layer may be a material selected based on the potentialof the cathode 110, such as aluminum or other suitable metals. In otherwords, the materials for the first and second metal layers can beselected based on the materials that are selected for the anode andcathode active materials.

The first and second metal layers can be made of any material known inthe art. For example, copper, aluminum, or stainless steel may be used.In instances where one or more metal layers have higher impedance thanother conductive metals, the metals used in the first and second metallayer can be the same or different. The materials selected for the anodeand cathode can be any suitable battery materials. For example, theanode material can be silicon, graphite, carbon, a tin alloy, a lithiumcontaining material, such as lithium titanium oxide (LTO), or othersuitable materials that can form an anode in a battery cell.Additionally, for example, the cathode material can be alithium-containing material. In some embodiments, the lithium-containingmaterial can be a lithium metal oxide, such as lithium cobalt oxide,lithium manganese oxide, lithium nickel manganese cobalt oxide, lithiumnickel cobalt aluminum oxide, or lithium titanate, while in otherembodiments, the lithium-containing material can be a lithium ironphosphate, a lithium metal polymer, or other suitable materials that canform a cathode in a battery cell.

The first and second metal layers may have any suitable thickness thatallows for a hermetic seal to be formed and provides suitable mechanicalstability to prevent failure, such as breakage of the layers, duringanticipated usage of the stacked battery. Additionally, the thickness ofthe metal layers can be sufficiently thin to allow for bending andflexing in the separation region to accommodate expansion anticipatedduring cycling of the stacked battery, including, for example, up to 10%expansion in the z-direction.

Turning to FIG. 2 , the stacked current collector 150 may have aconnection region 153 where the first metal layer 152 and second metallayer 154 may be connected, and a gap region 155 at the peripheral endsof the collector 150. In the connection region 153, the first metallayer and second metal layer may be joined to beelectrically-conductive. In some embodiments, the first metal layer andsecond metal layer may be directly connected, while in other embodimentsthe first metal layer and second metal layer may be indirectly connectedvia a conductive material. To form the connection region 153, the firstmetal layer 152 and the second metal layer 154 may be laminatedtogether. Additionally, the connection region 153 may be created bywelding the first metal layer 152 and the second metal layer 154together. The connection region 153 may also be created by using anadhesive, which is electrically conductive, between the first metallayer 152 and the second metal layer 154. In other embodiments, theconnection region 153 may be created by the wetting that can occurbetween the materials of the first metal layer 152 and the second metallayer 154.

In the gap region 155, the peripheral ends of the first layer 152 andthe second layer 154 may be spaced apart and moveable relative to eachother. As such, there may be a separation distance between the first andsecond metal layers, which may increase as the electrochemical cellswells. In some embodiments, the spaced apart peripheral ends of thefirst metal layer 152 and the second metal layer 154 may be of a lengththat is sufficient to accommodate an anticipated expansion of theindividual electrochemical cells of the stacked battery during cyclingof the battery. The peripheral ends 152 a and 154 a may have a length L,as shown in FIG. 2 , which may be long enough that up to or at leastabout 10% expansion in the z-direction can be accommodated.

As shown in FIG. 1 , each cell C1, C2, C3, and C4, also includes a seal140 to electrochemically isolate the electrochemical cells from eachother. Thus, each cathode-anode pair may be electrochemically sealed andisolated from neighboring electrochemical cells. Because the metallayers 152 and 154 may be separated at the peripheral ends, separateseals 140 can be formed on opposing sides, such as a top and bottom, ofthe stacked current collector 150.

The seal material may be able to bond with the first and second metallayers of the stacked current collector to prevent electrolyte leakage.The seal material may be a polymer, an epoxy, or other suitable materialthat can bond with first and second metal layers to create a hermeticseal. In some embodiments, the polymer may be polypropylene,polyethylene, polyethylene terephthalate, polytrimethyleneterephthalate, polyimide), or any other suitable polymer that may bondwith the first and second metal layers of the stacked current collectorto form a hermetic seal and may also provide resistance to moistureimpedance. The electrolyte may be a solid, a gel, or a liquid inembodiments. The seal may electrochemically isolate each electrochemicalcell by hermetically sealing the cell, thereby preventing ions in theelectrolyte from escaping to a neighboring electrochemical cell. Theseal material may be any material providing adequate bonding with themetal layers such that the hermetic seal may be maintained through apredetermined period of time or battery usage.

The separator may be soaked with the electrolyte, such as a fluidelectrolyte or gel electrolyte, to incorporate the electrolyte into thestacked battery. Alternatively, a gel electrolyte may coat theseparator. In still further alternatives, a gel electrolyte may coat thefirst metal layer and/or second metal layer before combination.Additionally, the electrolyte may be blended with particles of electrodeactive material. In various embodiments, incorporating the electrolyteinto the components of the stacked battery may reduce degassing in thestacked battery. In variations that include a flexible seal, the stackedbattery may accommodate gas resulting from degassing. Moreover,manufacture of the stacked battery may not require a separateelectrolyte fill step.

The individual electrochemical cells may be formed in any suitablemanner. In some embodiments, the cathode 110, the anode 120, and theseparator 130 may be preassembled. A first metal layer 152 may then beconnected to the anode while a second metal layer 154 may be connectedto the cathode to create a cell. The seal material may be disposedbetween the first metal layer 152 and the second metal layer 154 to formseals 140. Finally, the peripheral ends of the sealed electrochemicalcell may be further taped to frame the cell. Tapes 145 may be disposedaround the outer perimeter of the metal layers and seals. The tape 145may be substituted with ceramic or polymeric materials. Tape 145 may beincluded for various reasons including to prevent shorting, provideimproved electrochemical or chemical stability, and to providemechanical strength.

FIG. 3 illustrates a top plan view of a portion of an exemplary currentcollector 300 according to embodiments of the present technology, andmay represent a portion of a current collector within, for example,connection region 153 as previously described. The current collector 300may be a stacked current collector, or two connected current collectors,and may be coupled between a first cell and a second cell of a stackedbattery. As illustrated, current collector 300 may include a grid 305,which in embodiments may be an insulative grid. Current collector 300may additionally include a conductive material 310 disposed within theinsulative grid.

The insulative grid may have an electrode active material in contactwith the surface of the grid, which may be a cathode material 110 or ananode material 120 as previously described. The current collector 300may be a specific stacked current collector and have an anode activematerial in contact with one surface of the current collector 300, aswell as a cathode active material in contact with an opposite surface ofthe current collector. Additionally, the current collector 300 may beutilized in a stacked battery design as previously described, in whichit may be positioned proximate another current collector from anadjacent cell.

The configuration of current collector 300 may further affect electronicflow through the current collector. As previously noted, batteries suchas stacked batteries, including bipolar and MCS batteries, may directcurrent flow through the cell layers, whereas some conventional designsflow current across collectors and through tabs from each cell, whichmay include a bus bar coupling the tabs. Accordingly, in stackedbatteries, as flow proceeds from an active material layer through thecurrent collector 300, conductive material 310 may maintain conductivityto the following layer. Insulative grid 305 may substantially,essentially, or fully limit or prevent in-plane conductivity or currentflow across the current collector 300. Although the insulative grid 305may affect uniformity of current flow, this effect may be marginal orprevented by the cell design which may provide substantially or fullyuniform conductivity from the active material layer. Accordingly,insulative grid 305 may have a negligible effect on cell performance,while providing increased short-circuit protection as described furtherbelow.

During a nail penetration or other abusive event in which a cell isbreached, insulative grid 305 may fully limit the breach to thesurrounding regions of conductive material 310. By limiting flow acrossthe current collector 300, such as in the XY-plane, a short-circuitingevent may be confined. It is to be understood that such an event maylikely cause a full failure of the battery, however, the full failuremay be controlled to limit side effects of such failure events. For theease of understanding, the following description will provide a briefexplanation of the difference in outcome from a penetration event of aconventional battery design against the design including currentcollector 300. Although the description relates to a nail penetrationtest as often performed in battery abuse testing, it is to be understoodthat the examples may cover any type of penetration or breaching eventin which a short circuit may occur.

FIG. 4A displays a cross-sectional view of a conventional battery 400including foil current collectors. The individual cells of the batterymay include cathode current collector 405, and cathode active material410. The cells may also include anode current collector 415, and anodeactive material 420. Finally, the battery 400 may have separators 425between the electrodes. The anode and cathode current collectors 415,405 include tab portions extending from the collectors joined by busbars 408. In other designs, the tabs are coupled directly together withtabs of the same potential.

In such a conventional battery, the anode current collector 415 may becopper, and may be a uniform film across the cell. Similarly, thecathode current collector 405 may be aluminum, and also may be a uniformfilm across the cell. Were a failure event such as a nail penetration430 through the cell to occur, a short circuit would form at the site ofthe nail penetration, drawing surrounding current. However, conventionaldesigns couple the anode current collectors 415 together and couple thecathode current collectors 405 together. Because of this coupling, andthe highly conductive material used for the current collectors, theentire battery may discharge towards the short circuit. Current wouldeffectively proceed across the current collector to the short at aheightened rate, which would produce a concomitant temperature increaseat the site, and across the cell. Because of the high conductivity ofthe materials included in the battery, the short may occur quickly,which can thereby cause a similarly expedient temperature rise, whichcan lead to thermal runaway within the battery. Additionally, the largerthe battery, or the larger the number of cells, the more current may bedischarged in such an event, and the more heat generated.

FIG. 4B illustrates a temperature profile of a top plan view of battery400 during a failure event from nail penetration. The figure is includedto illustrate the accompanying temperature effect of the event acrossthe cathode tab and current collector. As shown, battery 400 includes acathode tab 435, which may be coupled cathode tabs from several cells.The battery 400 also includes an anode tab 440, which may be coupledanode tabs from several cells. The tabs are shown in FIG. 4A extendingfrom opposite sides of the cell for ease of description, although inmany cell designs the tabs are located on the same end of the battery asshown in FIG. 4B. The area of the puncture and short circuit 445 isillustrated as well as a view of a current collector 450 through whichthe puncture has occurred. As illustrated, the temperature profilerelates to the current flow within the battery. The short circuit allowssignificant current to flow through the tabs and current collectorlayers, causing heat to build up at the site of the puncture 445 andshort circuit, as well as at the tabs 435 where the current from coupledcells may flow.

The amount of flow during the short circuit may be related to the numberof cells coupled together and the architecture of the cell, however, theflow may reach well over 100 Ah/m², and result in temperature increasesof several hundred degrees or more. This may cause reactions to occurwithin the cell that are exothermic in nature, furthering the failureevent, and potentially causing a loss of integrity of the device, andpotentially other effects related to such a failure.

The current collector foils of battery 400 are unlikely to limit such afailure event. Typical foils of copper and aluminum have resistivitycharacteristics of roughly 1.7×10⁻⁸ and 2.7×10⁻⁸, respectively. Becauseof the lateral dimensions of the foils across which current must flow innormal operation, materials of such resistivity are used to limit thereduction in capacity of the battery. Were more resistive materialsused, not only would the capacity of the battery be reduced, but theincreased impedance would additionally reduce the speed of charging andincrease the heating during charge and discharge. Accordingly, thedirection of improvement for many such batteries, especially whenscaling, is to reduce resistance of flow across the current collectorsto, directly and indirectly, increase capacity and power. However, suchaccommodations also increase the charge transfer during discharge eventssuch as short circuit, which can cause complete device failures.

By utilizing current collectors designed to facilitate through-planecurrent flow while reducing in-plane current flow, the distance ofelectronic travel may be several orders of magnitude less than designsthat direct electronic flow from individual cells across currentcollectors and off tabs. Accordingly, for some stacked cell designs,maintaining certain thresholds of conductivity in the current collectorsto limit the effect on capacity and operation may no longer be an issue.As the distance of electronic travel from each cell decreases, theresistivity associated with electronic travel decreases as well. Thus,design modifications such as those identified and described in relationto the present technology may affect failure and abuse tolerances.

FIG. 5A shows a schematic cross-sectional view of a portion of a stackedMCS battery 500 during a fault event according to the presenttechnology. Battery 500 may include some or all components of battery100, for example. Battery 500 illustrates two cells according to thepresent technology, which may include a plurality of current collectors505 a-d, as well as a cathode material 510 and an anode material 520.Each cell may also include a separator 525 between the anode and cathodeactive materials. The current collectors of battery 500 may be currentcollectors according to FIG. 3 as previously described, although it isto be understood that the current collectors described elsewhere in thepresent disclosure may be similarly used based on the properties theyprovide.

The figure also shows a short circuit caused by a nail penetration 530,which may short across the cell. Complete failure of the battery mayoccur, however, effects associated with a failure event may beprevented. Upon a short circuit within the device, current may beprevented from flowing through the current collectors 505 in plane, ormay be afforded reduced flow in plane. For example, with the insulativegrid design, XY-plane current flow may be essentially prevented inembodiments, or substantially reduced. Additionally, normal operation ofsuch a cell design may provide current flow in the Z-direction acrosscomponents of the cell. Thus, when the short-circuit occurs, currentflow will still occur through each component towards the area of theshort circuit, but such current flow may be at a level that preventssubstantial heat generation in the device.

For example, resistivity of active materials in the cell may be ordersof magnitude higher than copper and aluminum. When the short-circuitoccurs, the battery may still fully discharge, but the flow profile maybe different within the battery. Instead of the flow of current acrosshighly conductive current collectors and tabs, flow may proceed in theZ-direction through the material layers of the cell towards the short.Because each current collector may not be coupled with one another viatabs, the current flow may be substantially less than 100 Ah/m², and maybe less than or about 50 Ah/m², less than or about 30 Ah/m², less thanor about 20 Ah/m², less than or about 10 Ah/m², less than or about 5Ah/m², or less in embodiments. At such levels of current flow, thetemperature may increase slightly during the fault-induced discharge,but the temperature within the device may be well within normaloperating tolerances for the device.

Moreover, the temperature increase at the site of the fault maysimilarly be maintained within acceptable ranges. Illustrated at FIG. 5Bis a top plan view of a heat profile of a portion of current collector505 a during the fault event and penetration of nail 530. As previouslydiscussed, the current collector 505 a may include an insulative grid507 in which is disposed a conductive material 509. The site of thepenetration short circuit 535 may still show an elevated temperature ascurrent discharges to this location. However, the temperature may bemaintained within acceptable tolerances because portions of theinsulative grid 507 may reduce or prevent any current flow across thecurrent collector 505 a to the site of the short circuit. Accordingly,electronic flow may instead proceed through active material layers tothe site of the short circuit, which may substantially reduce the timeof discharge, the electric charge transferred at the site of the shortcircuit, and the heat generated due to the charge transfer. Thesebenefits may be produced from several current collector designs of thepresent technology, which may include increased resistivity in theXY-plane compared to conventional designs, or protective devices withinthe structure. The remaining portions of the disclosure will discussseveral of these designs.

FIG. 6 shows an exemplary cross-sectional view along line A-A from FIG.3 of a current collector 600 according to embodiments of the presenttechnology. The current collector 600 may include an insulative grid605, and may include a conductive material 610 disposed within theinsulative grid 605. Insulative grid 605 may be composed of aninsulative material including a polymeric material or a ceramicmaterial. Additionally, insulative grid 605 may be one or more plasticmaterials including, as non-limiting examples, polyethylene,polypropylene, polyvinylchloride, other polymeric carbon-containingmaterials including rubbers, phthalate containing materials includingdiethylhexyl phthalate, halogen-containing polymers includingpolytetrafluoroethylene, fluorinated ethylene propylene, ethylenetetrafluoroethylene, perfluoroalkoxy, silicon-containing materials, orother insulating materials. Insulating grid 605 may also includecombinations of materials, such as those listed, to produce particularchemical and electrical properties. For example, the insulating grid maybe designed based on properties of the electrolyte with which it is incontact, as well as the electrical potential at which the currentcollector may operate.

Conductive material 610 may include any conductive material that myoperate within the current collector. In embodiments the conductivematerial 610 may include silver, copper, aluminum, iron, stainlesssteel, carbon particulates, or other conductive materials and metals aswould be understood by the skilled artisan. The conductive material 610may include composite materials including one or more of the listedmaterials, as well as polymeric and/or ceramic material. The compositematerials may be produced to provide a resistivity higher than purermaterials. As previously discussed, because the electronic conductivityoccurs in the Z-direction for the described batteries, the distancetraversed may be orders of magnitude less than in a conventionalbattery. Accordingly, utilizing materials with lower conductivity mayhave limited impact on cell capacity and performance, while providingbenefits including during failure events. Such materials may not beacceptable in conventional designs where increased conductivity is oftensought.

Current collector 600 may have an in-plane resistivity across a lengthin the XY-plane that is greater than or about 1×10⁻⁸ ohm-m inembodiments in which a material such as copper may be used. However,based on the cell operation, current collector 600 may have an in-planeresistivity across the current collector of greater than or about 1×10⁻⁷ohm-m, greater than or about 1×10⁻⁶ ohm-m, greater than or about 1×10⁻⁵ohm-m, greater than or about 1×10⁻⁴ ohm-m, greater than or about 0.005ohm-m, greater than or about 0.01 ohm-m, greater than or about 0.05ohm-m, greater than or about 0.1 ohm-m, greater than or about 0.5 ohm-m,greater than or about 1 ohm-m, greater than or about 10 ohm-m, greaterthan or about 100 ohm-m, greater than or about 1,000 ohm-m, greater thanor about 10,000 ohm-m, or more in embodiments. Additionally, currentcollector 600 may have an in-plane resistivity of between about 1×10⁻⁵ohm-m and about 1,000 ohm-m. Current collector 600 may also have anin-plane resistivity between about 0.005 ohm-m and about 1 ohm-m, orbetween about 0.05 ohm-m and about 1 ohm-m.

The insulative grid may control the in-plane resistivity, although theconductive material disposed within the grid may also impact theresistivity. In some embodiments, the conductive material may bemaintained fully within the conductive grid in embodiments, and eachregion of conductive material 610 may be fully isolated from proximateregions by the conductive grid 605. Additionally, current collector 600may be configured to maintain a liquid seal across the currentcollector. For example, the insulative grid 605 and conductive materialmay together form a liquid barrier across the current collector 600, andmay form a vapor barrier across the current collector in embodiments.

FIG. 7A shows an exemplary cross-sectional view of a current collector700 according to embodiments of the present technology. Currentcollector 700 may be similar to stacked current collector 150 previouslydescribed, and may include some or all aspects of that stacked currentcollector as well as some or all aspects of current collector 600previously described. Current collector 700 may include one or moreinsulative grids 705 a-b. Insulative grid 705 a may be directly coupledwith insulative grid 705 b, or insulative grid 705 a and insulative grid705 b may be a single continuous design. Within a battery, such as astacked battery, current collector 700 may include a first layer 702 incontact with a first cell of the stacked battery, and a second layer 704in contact with a second cell of the stacked battery. For example, firstlayer 702 may be in contact with an active material of the first cell,such as an anode active material, for example. Additionally, secondlayer 704 may be in contact with an active material of the second cell,such as a cathode active material, for example.

Current collector 700 may also include conductive materials 710 a-bdisposed within the current collector 700. Accordingly, each of firstlayer 702 and second layer 704 may include an insulative grid 705 havinga conductive material 710 disposed within the insulative grid. Inembodiments, conductive materials 710 a and 710 b disposed within theinsulative grid of the first layer 702 and the second layer 704 may besimilar materials or identical materials. As one non-limiting example,the conductive material 710 may be or include stainless steel in each offirst layer 702 and second layer 704. For example, an identicalconductive material 710 may be disposed within each insulative grid 705,or similar but tuned composite materials may be disposed in theinsulative grids. For example, because the two regions may be operatingat different potential, if a composite material is used, certaincomponents may be similar between the composites, but other materialsmay be different or adjusted to account for operation at the differentpotential. Identical composite material may additionally be used forconductive materials 710.

In other embodiments conductive material 710 a may be a differentmaterial than conductive material 710 b. For example, first layer 702may be in contact with an anode active material of a first cell. Theconductive material 710 a within the insulative grid of first layer 702may be a material that may operate at anode potential in a stackedbattery, and may be or include copper, stainless steel, acarbon-containing material, or a composite having electricalcharacteristics based on anode potential. Similarly, for example, secondlayer 704 may be in contact with a cathode active material of a secondcell. The conductive material 710 b within the insulative grid of secondlayer 704 may be a material that may operate at cathode potential in astacked battery, and may be or include aluminum, stainless steel, acarbon-containing material, or a composite having electricalcharacteristics based on cathode potential. Any other material that mayaffect electrical characteristics of the current collector may also beused in either conductive material 710 as would be understood by theskilled artisan.

Between first layer 702 and second layer 704 may be an interface 715.Interface 715 may be a fluid impermeable interface between the twolayers. For example, first layer 702 and/or second layer 704 may befluid impermeable, and thus the interface 715 may be fluid impermeable.Another design is illustrated in FIG. 7B, and shows an exemplarycross-sectional view of another current collector according toembodiments of the present technology. Current collector 750 may besimilar to current collector 700, and may include a first layer 702having insulative grid 705 a and conductive material 710 a. Currentcollector 750 may additionally include second layer 704 havinginsulative grid 705 b and conductive material 710 b. Any of thematerials and characteristics of stacked devices previously describedmay be included in current collector 750. Current collector 750 may alsoinclude layer 760 disposed between first layer 702 and second layer 704.Layer 760 may be a coupling material, such as an adhesive, and may alsobe a barrier layer between the first layer 702 and the second layer 704.A barrier layer may include material that is fluid impermeable, and thusmay be an ionic barrier, but may not be an electronic separator orbarrier. Accordingly, in embodiments layer 760 may be at least partiallyconductive. The layer 760 may also provide additional safetyfunctionality between a first cell and a second cell utilizing thestacked current collector 750.

Layer 760 may also provide a fusing or separator mechanism between afirst cell and a second cell in embodiments. For example, layer 760 maybe or include a layer of positive temperature coefficient (“PTC”)material positioned between the first layer 702 and the second layer 704of the stacked current collector 750. The PTC fusing capability inregion 750 may operate to separate adjoining cells during fault eventssuch as previously described. The PTC material may include a polymerthat is itself conductive at low temperature, but which becomes highlyresistive at increased temperature. Thus, when the temperature returnsto normal operating conditions, the polymer may recover its conductiveproperties. This may not matter for fault events causing permanentfailure of a battery, but electronically separating the individual cellsof the battery by electrically decoupling the stacked current collectorlayers between each cell may reduce the influx of current and associatedheat increase of a fault event. The PTC material may also be designed toallow minimal resetting, or be non-resettable in embodiments. Thus, thePTC material may be able to overcome the temperature increase of amomentary event, however the PTC material may be configured so thatduring major fault conditions like overcurrent or short-circuit, the PTCmaterial may be activated, or may physically separate the cells toprevent any electronic flow between cells. In order to provide thenon-resettable characteristics of the PTC material that may be locatedin or may be layer 760, the layer of PTC material may be modified withcharacteristics intended to ensure the fuse does not reset.

For example, under normal operating temperatures, the PTC layer mayimpart an impedance of less than or about 1 milliohm, less than or about0.1 milliohms, less than or about 0.01 milliohms, or between about 0.001milliohms and about 0.1 milliohms. As the temperature exceeds acceptablelimits of the normal operating window, such as by an increasedelectronic flow that causes heat generation at a particular location orwithin a layer of a cell, the PTC layer may provide an increasedimpedance as the structure of the PTC layer adjusts due to the increasedtemperature. For example, the impedance may increase to more than orabout 1 megaohm, more than or about 5 megaohms, more than or about 10megaohms, more than or about 20 megaohms, or more than or about 50megaohms by separating the conductive materials, such as carbon, withinthe structure of the material. This may also provide a resettablestructure in that as the temperature decreases, the impedance may alsodecrease to the original conditions.

The PTC material may include additional materials in addition to thepolymeric materials discussed. For example, the polymeric materials mayprovide a structure that incorporates and contains additional conductivematerial mixed with the binder or polymer of the PTC material. Theconductive material may aid operation of the conductive path duringnormal operation, and allow electrical flow across the PTC material. Forexample, conductive material may include a powder of conductive materialthat is mixed with the polymeric structure. The conductive material mayprovide enhanced conductive paths through the PTC material in order tomaintain a low impedance through the fuse element. The conductivematerial may be particulate or powders of conductive materials includingsilver, copper, zinc, nickel, carbon-containing materials includingcarbon black, or other conductive materials that may be admixed withpolymeric components such as those previously discussed.

Upon realizing temperatures that exceed a determined operating windowfor an exemplary stacked battery, the polymeric structure may swellsufficiently to separate or isolate the conductive material, which mayproduce an impedance increase sufficient to interrupt current flowthrough the device. The swelling of the PTC material may be on the orderof a few microns, for example, or more in embodiments. The PTC materialmay be contained between current collector layers 702 and 704 at athickness of from about 1 μm to about 50 μm in embodiments. Thethickness of the PTC material may also be from about 3 μm to about 30μm, or from about 5 μm to about 20 μm. The swelling may be less thanabout 20 μm increase in thickness, less than about 15 μm increase inthickness, less than about 10 μm increase in thickness, less than about5 μm increase in thickness, or less than about 1 μm increase inthickness. The swelling may produce a reduction in the bonding strengthof the PTC material. Thus, when used in non-resettable embodiments, theswelling of the PTC material may not revert when the temperature isreduced, and may permanently interrupt current across the stackedcurrent collector between or associated with two adjacent cells.

FIG. 8 shows an exemplary cross-sectional view of two battery cells 800according to embodiments of the present technology. Battery cells 800may be similar to any of the previously described embodiments, and maybe cells included in any of the battery structures previously described.For example, battery cells 800 may be two of many cells in a stackedbattery, such as discussed with respect to FIG. 1 , for example. Batterycells 800 may include two first current collectors 805 a and two secondcurrent collectors 805 b. The current collectors 805 may be portions ofthe stacked current collectors previously described. For example,current collector 807 may be a single stacked current collector, or maybe first and second layers of a stacked current collector as previouslydescribed.

Each current collector 805 may include an insulative grid 810 in which aconductive material 815 is disposed, similar to the design discussedpreviously. Each current collector 805 may have similar or differentmaterials included as or with the insulative grid 810 as well as withthe conductive material 815. In other embodiments, current collectors805 may have different materials or variations on materials. Forexample, current collectors 805 a may include a similar material for theconductive material 815 a, and current collectors 805 b may include asimilar material for the conductive material 815 b. As one non-limitingexample, current collectors 805 a may include an aluminum material orcomposite as the conductive material 805 a, and current collectors 805 bmay include a stainless steel material or composite as the conductivematerial 805 b. Other variations as previously discussed are similarlyencompassed, as would be readily apparent to the skilled artisan.

Each cell of battery cells 800 may include a cathode material 820, andanode material 825, and a separator 830 within the cell. Any of thepreviously discussed materials may be utilized in the battery cellelectrodes. Additionally, each current collector, including stackedcurrent collector 807 may include a coupling material 835 positionedabout a perimeter of the insulative grid. Coupling material 835 mayinclude a polymeric material that extends about an exterior ofinsulative grid 805 of each current collector, or current collectorlayer, such as for the stacked current collector 807. Coupling materialmay provide an insulation material for joining the cells of the battery.

As previously discussed with respect to FIG. 1 , for example, thestacked battery cells may include a gap region 155 at an exterior of thecurrent collector materials. The material in the gap region may be usedto seal the cells of the stacked battery. In the design discussed inthat figure, a seal 140 may be included along with a tape 145 toelectrically protect the current collectors, which may be conductivefrom shorting to adjoining layers. The seal 140 and tape 145 may fluidlyseal the cell of the battery cell, and may also provide an electricalbarrier between the current collectors of the cell. Coupling material835, however, may obviate the need for the seal 140 as well as the tape145, although in some embodiments the stacked design may include seal140 and tape 145.

Coupling material 835 may include a polymer such as an insulatingpolymer that may be coupled, bonded, or otherwise connected with or to acoupling material 835 from the opposite current collector of theindividual cell. Unlike conductive current collector materials, couplingmaterial 835 may not pose a risk of electrically shorting the cell, asthe coupling material 835 may be insulative, and coupling material 835may electrically separate the cells from each other in a way similar toseal 140 and tape 145 discussed above. The coupling material 835 may becoupled with the individual current collector during manufacturing, andthen subsequent cell assembly may be joined with the coupling material835 of the paired current collector of the cell. For example, couplingmaterial 835 may be joined or bonded with a conductive current collectorsuch as illustrated in FIG. 1 , and may also be joined with aninsulative material, which may similarly be a polymeric material, suchas with insulative grid 805 or 507 as previously described.

Coupling material 835 may include any number of polymeric components orcombinations to provide useful characteristics for the couplingmaterial. For example, the coupling material 835 may include any of thepreviously described insulative materials. Coupling material 835 mayinclude polyolefins such as polypropylene, polyethylene, or otherthermoplastic olefins or elastomers including butyl compounds such asisobutylene, isoprenoids, or other compounds that may impart particularcharacteristics on the coupling material. For example, compounds may beincluded to provide stability of the material within the electrolyticsubstances. Compounds, monomers, or functional groups may also beincluded to provide sealant characteristics, flexibility, stiffeners, orother functional characteristics useful in a coupling material.

During manufacturing or production, the coupling material 835 may beheat sealed, pressure sealed, bonded, adhered, or otherwise joined withthe coupling material 835 of the other current collector of the batterycell. Once joined, the coupling material may provide a liquid and/orvapor seal about the battery cell, and may reduce the material andproduction costs associated with joining conductive current collectors.By reducing the area of the current collector to the area of theoperating cell itself, the coupling material 835 may be used to providethe sealing and protection of the cell without additional materials.Such a coupling material may be utilized with any of the currentcollector configurations or designs discussed throughout the presentapplication, as well as many other designs that would benefit from thecharacteristics discussed.

Turning to FIG. 9 is shown a top plan view of a portion of a currentcollector 900 according to embodiments of the present technology.Current collector 900 may be used in a multi-cell battery or single-cellbattery including any of the stacked battery configurations previouslydescribed. For example, an exemplary multi-cell battery may include afirst cell including a first current collector, a first anode, a firstcathode, and a second current collector. The exemplary multi-cellbattery may also include a second cell including a third currentcollector, a second anode, a second cathode, and a fourth currentcollector. One or more additional cells may be included in themulti-cell battery in embodiments as well. Several of the figuresinclude structures illustrating these features. Such as in any of thepreviously discussed stacked configurations, the second currentcollector and the third current collector of the multi-cell battery maybe coupled with one another across a surface of each of the secondcurrent collector and the third current collector. Current collector 900may be any one up to all of the current collectors in the exemplarymulti-cell battery, or in any of the configurations discussed elsewherein the disclosure. Additionally, any of the other described currentcollector designs may be used or combined in cells or across cells inthe battery in a variety of combinations.

Current collector 900 may include a conductive grid 905. In someembodiments conductive grid 905 may be disposed in an insulativematerial 910. The conductive grid 905 may be or include a weave ofconductive wires or fibers, a welded number of conductive elements, adeposited array of conductive elements, or a layered number ofconductive elements that may be disposed within the insulative material910. In some embodiments the conductive elements may be fully disposedwithin the insulative material, and may be completely surrounded byinsulative material 910, such that no portion of conductive grid 905 maybe directly in contact with any other material of a cell. Additionally,the insulative material 910 may be coated about the conductive grid 905allowing a surface of the grid 905 to be exposed to contact additionalcomponents, such as active material layers of the cell. Additionally,current collector 900 may include a coupling material positioned about aperimeter of the insulative material as previously discussed.

The current collector 900 may include any of the previously describedconductive materials to impart conductive characteristics to the currentcollector 900. For example, in embodiments each current collector of anexemplary multi-cell battery may include current collector 900, andconductive grid 905 may be the same or a similar material in eachcurrent collector. In one non-limiting example, a similar material maybe stainless steel or a conductive composite material that may becapable of or configured to operate at both anode and cathode potential.Additionally, the conductive grid 905 may be different materials fordifferent current collectors. For example, in an exemplary multi-cellbattery such as identified above, the first current collector and thethird current collector may include a first material in the conductivegrid. Additionally, the second current collector and the fourth currentcollector may include in the conductive grid a second material differentfrom the first material. For example, in one non-limiting embodiment,the first material may be aluminum, and the second material may bestainless steel or copper.

The insulative material 910 may include any of the polymeric orinsulative materials discussed elsewhere in the disclosure. Thecombination of the conductive grid 905 and the insulative material 910may provide a fluid impermeable current collector in embodiments, andmay provide a vapor barrier, while allowing electronic conductivityacross the current collector 900. The current collector 900 may providean amount of conductivity in the XY-plane of the current collector 900in part from the conductive grid that extends continuously through thecurrent collector. In some embodiments the dimensions and materials ofthe conductive grid 905, as well as the properties and coverage of theinsulative material 910, may be used to adjust the conductivity of thecurrent collector 900.

As previously discussed, the current collector 900 may be used in astacked battery design in which the electronic flow is in theZ-direction of the cell components, which may be of a smaller dimensionthan in an XY-plane. Accordingly, by reducing the conductivity of thecurrent collector 900, safety protections may be imparted to the currentcollector without affecting, or without critically affecting, the cellcapacity or performance. In embodiments, the conductive grid 905 andinsulative material 910 may be configured to provide an in-planeresistivity across a length in the XY-plane that is greater than orabout 1×10⁻⁸ ohm-m in embodiments in which a material such as copper maybe used, and may be fully exposed from the insulative material. However,based on the cell operation, current collector 900 may have an in-planeresistivity across the current collector of similar units as discussedpreviously for current collector 600. For example, current collector 900may have an in-plane resistivity of between about 1×10⁻⁵ ohm-m and about1,000 ohm-m. Current collector 900 may also have an in-plane resistivitybetween about 0.005 ohm-m and about 1 ohm-m, or between about 0.05 ohm-mand about 1 ohm-m.

In some embodiments current collector 900 may additionally include acurrent interrupt component within or associated with the currentcollector. One or more current collectors of the exemplary multi-cellbattery may include a current interrupt device within or associated withthe current collector, and in embodiments each current collector 900 mayinclude or be associated with a current interrupt component. Forexample, a current interrupt component may include a PTC material aspreviously described. In embodiments, a PTC material may be disposedwith the insulative material 910, and may be incorporated into theinsulative material 910 or may be disposed on the insulative material910. The PTC material may be configured to expand at a predeterminedtemperature and separate the current collector from an adjacentcomponent layer.

The PTC material may be incorporated uniformly within the insulativematerial 910, or may reside in regions of the insulative material 910.For example, the PTC material may be located in a plurality of regionsof the insulative material, and when activated as previously describedmay electrically isolate or separate the current collector from adjacentcomponents. The PTC material may be disposed on one or both surfaces ofthe current collector 900 in contact with adjacent material layers inembodiments. Additionally, the PTC material may be disposed betweenadjoining current collectors of a stacked current collector. Forexample, with reference to the above-identified multi-cell battery, thePTC material may be disposed between the second current collector andthe third current collector. In embodiments, the PTC material may beconfigured to expand at a predetermined temperature to electricallydecouple the first cell and the second cell. The predeterminedtemperature of the PTC material activation may be based on an operatingwindow for the battery cell or coupled battery. For example, thetemperature may be based on the materials included within the cell orcells, but may be based on an operating window. In embodiments, the PTCmaterial may be configured to activate at a temperature below about 500°C., below about 400° C., below about 300° C., or lower depending ontemperature effects on constituent components.

Additional current interrupt components may include features of theconductive grid 905 itself. Illustrated in FIG. 10A is shown anexemplary schematic detailed view of region B from FIG. 9 of a currentcollector conductive grid 1005 a according to embodiments of the presenttechnology. As illustrated, the conductive grid may include a currentinterrupt component that may be the conductive grid itself. For example,the current interrupt component may include a plurality of regions ofthe conductive grid 1005 that may be characterized by reduceddimensions. The conductive materials included or composing theconductive grid 1005 may be sized to operate or configured to provide afusing capability within the current collector. For example, by reducinga wire size within the grid, heat generated by a high-current event,such as a short-circuit, may cause regions of the conductive grid tobreak, which may reduce or interrupt current flow through the currentcollector.

For conductive grid 1005 a, the grid may include a plurality of crossedgrid members 1007, 1008. The plurality of regions of the conductive grid1005 a may include parallel grid members 1008 characterized by a gridmember thickness less than a grid member thickness of parallel crossinggrid members 1007. The grid may be positioned such that the thicker gridmembers 1007 are positioned in a direction such that they contact theactive material and grid members 1008, but may not contact otherconductive materials. During a fault event across conductive grid 1005a, such as a short-circuit for example, heat may be generated due tocurrent flow across the conductive members 1007, 1008. Due to thereduced size of grid members 1008, the members may heat more rapidlythan grid members 1007. At a temperature that may be determined to causea trip event of grid members 1008, the grid members may separate orbreak between grid members 1007, which may electrically insulate thegrid members 1007 from one another. In this way, current flow across thecurrent collector 1005 a may be reduced, and generated heat may bedissipated, or may be prevented from further increases that may causefurther issues within the battery cell.

FIG. 10B shows an exemplary schematic detailed view of region B fromFIG. 9 of a current collector 1005 b according to embodiments of thepresent technology. As illustrated, conductive grid 1005 b may alsoinclude a plurality of crossed grid members 1009, 1010. The plurality ofregions of reduced dimensions may include portions 1012 of the gridmembers located between grid nodes 1015. Portions 1012 may be similar tofuse elements in which the dimensions of the region may cause heatbuildup, and failure or breakage at certain current flow or associatedtemperature. For example, during a fault event across conductive grid1005 b, heat may be generated due to current flow across the gridmembers 1009, 1010.

Due to the reduced dimensions of portions 1012, those regions may heatmore rapidly than the portions around nodes 1015. At a current flow orassociated temperature that may be determined to break or trip portions1012, the portions 1012 may break and electrically isolate regions orthe entire current collector 1005 b. In both exemplary conductive grids1005, the plurality of regions of reduced dimensions may be continuousacross the conductive grids, or may be selectively positioned about theconductive grids. For example, portions 1012 of conductive grid 1005 bmay be included after every other grid node 1015, as opposed to betweenevery grid node 1015. Because a trip event may fully isolate regions ofthe conductive grid 1005 b, the regions may include larger sections ofthe conductive grid, which may reduce material or production costs informing the plurality of regions of reduced dimensions. Aspects of thegrids of FIGS. 10A and 10B may be combined, and encompass examples only.Additional fusing or tripping components encompassed by the presenttechnology may also be incorporated within the grid as would beunderstood by the skilled artisan.

Turning to FIG. 11 is shown a cross-sectional view of an exemplarybattery 1100 according to embodiments of the present technology.Exemplary battery 1100 may include another current collectorconfiguration that may provide adjusted or modified in-plane currentflow according to the present technology. Battery 1100 may include afirst cell 1110 including a first current collector 1115 coupled with afirst cathode material 1120. First cell 1110 may also include a secondcurrent collector 1125 coupled with a first anode material 1130. Firstcell 1110 may also include a separator 1135 disposed between the cathodematerial 1120 and the anode material 1130.

Battery 1100 may further include a second cell 1150 including a thirdcurrent collector 1155 coupled with a second cathode material 1160.Second cell 1150 may also include a fourth current collector 1165coupled with a second anode material 1170. Second cell 1150 may alsoinclude a separator 1175 disposed between the cathode material 1160 andthe anode material 1170. As illustrated, the second current collector1125 and the third current collector 1155 may be coupled with oneanother.

An optional layer 1180 may be positioned between the second currentcollector 1125 and the third current collector 1155, or the two currentcollectors may be directly coupled with one another. Optional layer 1180may include a sealing or coupling material as previously explained thatmay provide a fluid seal between the first cell 1110 and the second cell1150. Additionally, each current collector may include a couplingmaterial 1185 positioned about a perimeter of the current collector,such as discussed previously with regard to FIG. 8 In embodiments, thecoupling material 1185 may include a polymeric material, and may be orinclude, for example, a polyolefin. The materials utilized in the anodeand cathode materials may be any of the previously described materials.

The current collectors of battery 1100, including for both first cell1110 and second cell 1150 may include an insulative matrix containing aconductive material within interstices of the insulative matrix. FIG. 12shows an exemplary schematic detailed view of region C from FIG. 11 of acurrent collector according to embodiments of the present technology. Asillustrated, current collector 1200 may include a matrix material 1205that may be insulative. The current collector 1200 may also includeconductive material 1210 incorporated within the matrix 1205, such ascontained within interstices of the insulative matrix 1205.

The insulative matrix 1205 may include a polymer disposed as the matrixmaterial or as part of the matrix material. The polymer matrix may bedeveloped with a conductive material to produce a current collectorhaving particular electrochemical or composite properties. For example,conductive particulate material may be admixed with the polymer materialin a fluid stage. The polymer material may then be formed and cured as acurrent collector insulative matrix 1205, which may include theconductive material 1210 within the matrix. The conductive material mayinclude any of the conductive materials previously identified. Inembodiments, the conductive material may include one or more of silver,aluminum, copper, stainless steel, and a carbon-containing material.Coupling material 1185 may be the same material or a different materialas the current collector matrix material 1205 in embodiments. Forexample, coupling material 1185 may be or include insulative matrix1205, but may include an unfilled insulative matrix that may not includeconductive material 1210. Coupling material 1185 may also include amodified version of the insulative matrix 1205 in order to provideadditional features or functionality as previously described. Couplingmaterial 1185 may also include a material as previously discussed thatmay be coupled with, bonded to, or joined with current collector 1200insulative matrix 1205.

Insulative matrix 1205 containing conductive material 1210 may provide auniform conductive profile throughout the current collector 1200.However, based on the inclusion of conductive material, as well as theproperties of the matrix material, the current collector 1200 may have atuned resistivity to provide similar characteristics as otherconfigurations discussed throughout the present disclosure. For example,the produced current collector 1200 may be configured to provide anin-plane resistivity across a length in the XY-plane, as well as athrough-plane resistivity in the Z-direction, which is greater than orabout 1×10⁻⁴ ohm-m in embodiments. In other embodiments, currentcollector 1200 may have an in-plane resistivity across the currentcollector and a through-plane resistivity of similar units as discussedpreviously for current collector 600 and 900. For example, currentcollector 1200 may have an in-plane and through-plane resistivity ofbetween about 1×10⁻³ ohm-m and about 1,000 ohm-m. Current collector 1200may also have an in-plane and through-plane resistivity between about0.05 ohm-m and about 1 ohm-m, or an in-plane and through-planeresistivity of about 0.5 ohm-m in embodiments. Finally, althoughillustrated separately for ease of description, it is to be understoodthat any combination of the current collectors described may be utilizedin a battery cell, or in different cells within a single battery.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. For example, embodiments of current collectors describedabove may be incorporated into battery packs of other stacked designssuch as bipolar and MCS batteries. Additionally, a number of well-knownprocesses and elements have not been described in order to avoidunnecessarily obscuring the present technology. Accordingly, the abovedescription should not be taken as limiting the scope of the technology.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included. Where multiple values areprovided in a list, any range encompassing or based on any of thosevalues is similarly specifically disclosed.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a material” includes aplurality of such materials, and reference to “the cell” includesreference to one or more cells and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

What is claimed is:
 1. A multi-cell battery comprising: a first cellincluding a first current collector, a first anode, a first cathode, anda second current collector; and a second cell including a third currentcollector, a second anode, a second cathode, and a fourth currentcollector, wherein the second current collector and the third currentcollector are coupled with one another across a surface of each of thesecond current collector and the third current collector, wherein thesecond current collector and the third current collector each comprise aconductive grid, and wherein the second current collector includes acurrent interrupt component that, when activated, interrupts currentflow from the second current collector to the third current collector.2. The multi-cell battery of claim 1, wherein the conductive grid ofeach of the second current collector and the third current collector isdisposed in an insulative material.
 3. The multi-cell battery of claim2, wherein the current interrupt component comprises a positivetemperature coefficient (“PTC”) material disposed with the insulativematerial, and wherein the PTC material is configured to expand at apredetermined temperature and separate the second current collector fromthe third current collector.
 4. The multi-cell battery of claim 1,wherein the first current collector and the third current collectorcomprise a first material in the conductive grid, and wherein the secondcurrent collector and the fourth current collector comprise in theconductive grid a second material different from the first material. 5.The multi-cell battery of claim 4, wherein the first material isaluminum and the second material is stainless steel.
 6. The multi-cellbattery of claim 1, wherein the conductive grid of each currentcollector is the same material.
 7. The multi-cell battery of claim 1,wherein the conductive grid comprises first grid members and second gridmembers, and wherein the first grid members comprise a current interruptcomponent.
 8. The multi-cell battery of claim 7, wherein the conductivegrid comprises first grid members crossed with second grid members, andwherein first grid members are characterized by a thickness less than athickness of the second grid members.
 9. The multi-cell battery of claim1, wherein the current interrupt component comprises a non-resettablepositive temperature coefficient (“PTC”) material disposed between thesecond current collector and the third current collector, and whereinthe PTC material is configured to expand at a predetermined temperatureto electrically decouple the first cell and the second cell.